Remove Old Plugin – Fail | Solution w/ chown ?

Helllllo WordPressers,
So there seems to be a long standing issue with errors on removing old WordPress plugins when trying to do automatic updates. I have searched far and wide for a solution, and have found one… but have no idea what to do with it, and would love your lovely advice.

I have been having some trouble with my server permissions in my WordPress install that has caused some problems with upgrading plugins. My question is, I found a solution to said problem that included doing a line of code like so:

chown -R www-data:www-data /var/www

Problem is, I have no idea how to do this. I understand it will fix my server issues with permissions, but I am not sure how. Where do I add this code? What do I do with this? What if my servers are windows based and not apatche?

Information from:
http://philipoakley.org/2010/10/15/wordpress-2/wordpress-plugin-upgrade-failed-error-finally-solved/
http://www.wpcub.com/solved-remove-old-plugin-wordpress-error/

Any help or advice would truly be appreciated.

With love and admiration,
Laura 😀